Subversion Repositories klc32

// ============================================================================

// (C) 2011 Robert Finch

// All Rights Reserved.

// robfinch<remove>@opencores.org

//

// KLC32 - 32 bit CPU

// INTA.v - interrupt acknowledge

//

// This source file is free software: you can redistribute it and/or modify 

// it under the terms of the GNU Lesser General Public License as published 

// by the Free Software Foundation, either version 3 of the License, or     

// (at your option) any later version.                                      

//                                                                          

// This source file is distributed in the hope that it will be useful,      

// but WITHOUT ANY WARRANTY; without even the implied warranty of           

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            

// GNU General Public License for more details.                             

//                                                                          

// You should have received a copy of the GNU General Public License        

// along with this program.  If not, see <http://www.gnu.org/licenses/>.    

//                                                                          

// ============================================================================

//

INTA:

        if (!cyc_o) begin

                fc_o <= 3'b111;

                inta_o <= 1'b1;

                cyc_o <= 1'b1;

                stb_o <= 1'b1;

                sel_o <= 4'b0001;

                adr_o <= {27'h7FFFFFF,iplr,2'b00};

        end

        else if (vpa_i) begin

                inta_o <= 1'b0;

                cyc_o <= 1'b0;

                stb_o <= 1'b0;

                sel_o <= 4'b0000;

                vecnum <= 32'd24 + iplr;

                state <= FETCH_VECTOR;

        end

        else if (ack_i) begin

                inta_o <= 1'b0;

                cyc_o <= 1'b0;

                stb_o <= 1'b0;

                sel_o <= 4'b0000;

                vecnum <= dat_i[7:0];

                state <= FETCH_VECTOR;

        end

        else if (err_i) begin

                inta_o <= 1'b0;

                cyc_o <= 1'b0;

                stb_o <= 1'b0;

                sel_o <= 4'b0000;

                vecnum <= 32'd24;               // Spurious interrupt

                state <= FETCH_VECTOR;

        end

FETCH_VECTOR:

        if (!cyc_o) begin

                fc_o <= 3'b101;

                cyc_o <= 1'b1;

                stb_o <= 1'b1;

                sel_o <= 4'b1111;

                adr_o <= {vecnum,2'b00};

        end

        else if (ack_i) begin

                cyc_o <= 1'b0;

                stb_o <= 1'b0;

                sel_o <= 4'b0000;

                vector <= dat_i;

                state <= TRAP1;

        end

        // I don't bother with bus error checking here because if the cpu can't read the

        // vector table, bus error processing won't help.